1. Field of the Invention
The present invention relates to sealing arrangements for high voltage fuses.
2. Description of the Prior Art
High voltage expulsion type fuses are well known in the art as exemplified by U.S. Pat. No. 3,267,235 -- Barta and U.S. Pat. No. 3,855,563 -- Cameron. Such high voltage fuses typically comprise a fusible element electrically connected between a bottom ferrule and an arcing rod in such a manner that the arcing rod moves rapidly under the urging of a spring when the fusible element melts during fuse operations. The arcing rod is designed to puncture an upper sealing arrangement to trip a fuse latch to allow the expulsion fuse to drop out of its upper terminal mounting under the force of gravity. This sealing arrangement is important because the fuse is typically mounted outdoors and subjected to adverse weather conditions. If this sealing arrangement leaks, moisture can enter the fuse causing deteriorations of the interior components. The prior art sealing arrangements typically have comprised an annular ring mounted in the upper end of the fuse having an opening at the center thereof. A thin metal disk is soldered over the opening to complete the seal and to provide a thin portion for penetration by the arcing rod. The soldering operation is, of course, quite critical since an improper solder joint will result in a faulty seal.
It has been discovered that such prior art sealing arrangements are not entirely satisfactory since a reliable solder connection is difficult to manufacture and the seal is often broken during handling. Accordingly, it would be a desirable advance in the art to provide a sealing arrangement for a high voltage fuse which eliminates the deficiencies of the prior art.